1. Field of the Invention
This invention relates generally to infrared communications systems and, more specifically, to a Method and System for Preventing Burn-out of Infrared Transmitter Diodes.
2. Description of Related Art
As technology becomes continually more accessible to the "common man," the ability to use, store, transfer and otherwise manipulate information has become the focus of most businesses as well as for the individual consumer. Access to the information resources is commonly by some sort of network system, including World Wide Web, "Intranets", local area networks, wide area networks, as well as corporate databases.
While the conventional method for connecting to one of these information networks has been via cable and wire, as the reliance upon connectivity to information has deepened, the desire to gain such access from mobile or portable devices has strengthened. These portable devices, such as Personal Digital Assistants, hand-held computers, cellular telephones, and even digital cameras are now being connected to each other and to networks via Infrared Data Communications. In fact, it is virtually impossible to purchase a notebook computer today that does not include an Infrared Data Communications assembly resident within it.
FIG. 1 depicts a significant problem with the conventional Infrared-enabled appliance; it is an illustration of such an appliance 10. In its pertinent form, the typical Ir-enabled appliance 10 includes an infrared transceiver system 12 that is, for the purposes of this discussion, provided electrical power 14 by a power supply means 16, such as an internal battery or an external cable. Within the transceiver system 12, among other devices and circuits, there are typically at least one infrared transmitter 18 (or transmitter array) and at least one receiver 20 (or receiver array).
Under normal transmission conditions, when the Central Processing Unit 22 (or other control device or system) sends data to the communications controller 24 for transmission by the Ir transmitter 18, the controller 24 converts the data into a transmit data signal 26. A transmit data signal 26 is essentially a string of "power-off's" and "power-on's", which represent digital zero's and one's, respectfully. A "power-on" causes the transmitter 18 to emit an infrared signal 28. While transmitting normally, these "power-on's" and "power-off's" are of very short duration--on the order of less than one-tenth (0.1) second each.
Under certain power-up modes, however, the appliance 10 may direct or otherwise cause the power 14 to be energized to the transceiver 12, and more specifically, to create a "power-on" to the transmitter 18 for a substantial period of time. Furthermore, it is somewhat common for the CPU 22 to "lock up" or otherwise go into a "hang mode" during a variety of operations (or error conditions)--sometimes this, too can create a "power-on" condition in the transmitter 18.
The problem addressed by the present invention relates to the damage incurred by the transmitter 18 when the appliance is undergoing one of these power-up modes. It has been observed that the transmitter diode temperature 28 (represented by the thermometer here) of the typical infrared transmitter 18 will reach dangerously high levels if the transmit data signal 26 to the transmitter 18 is left in the "power-on" condition for periods in excess of 5 to 10 seconds. After being subjected to these high temperatures 22, particularly on a repeated basis, the typical transmitter 18 will fail due to thermal burn-out. What is needed is an improved transceiver system and method to prevent transmitter over-temp and subsequent failure due to prolonged "power-up" conditions.